Bar owners have a problem monitoring the amount of beer dispensed by the bartender, without some form of metering device. First, the owner depends upon the distributor to deliver a full keg of beer. The owner then incurs some loss when tapping the keg. He then assumes that each mug of beer that is filled, contains 8 oz., 10 oz., and so forth of the liquid. Lastly, he assumes that the bartender collects the money on every mug poured.
Each part of the process has inherent difficulties and contributes to a possible loss of income to the bar owner.
For example, if the owner assumes that he is getting a full keg of beer, roughly 1984 oz. but the distributor is shorting him by 20 oz. for each keg delivered, the equivalent loss is 1 percent.
Secondly, he expects to lose 20 oz. to tap the keg and eject the air from the supply line connecting the keg to the tap. This is another 1 percent.
Third, when filling the mug, at least 5 percent is lost to foaming and spillage. Further, about 5 percent of the mugs are dispensed without collecting any money.
Adding up all the losses, the bar owner can expect to lose about 12 percent. The largest contributor to this loss is spillage and unaccounted income, about 10 percent.
These losses are presently commercially undetectable, and are usually absorbed by the bar owner. Where the owner initially spends $35 for a keg, the dispensing process increases the actual costs to about $40 for a keg. This may not seem much to a small bar owner, but for a large corporation such as an airport, stadium, concert hall or the like, the owner can expect to go through 20 plus kegs per hour and the losses increase dramatically.
Metering beer by volume is inaccurate because the volume varies according to temperature, the amount of foaming and the like.
Metering the weight of the liquid in the mug, as it is being filled, is unsatisfactory because of the erratic momentum of the beer striking the mug.